Systems, devices and methods for the treatment of neurological disorders and conditions

ABSTRACT

The present disclosure relates to methods, devices, and systems used for the treatment of and/or promoting recovery from various neurological disorders and conditions, including epilepsy and other seizure disorders and movement and other related disorders; for promoting recovery from acute or chronic brain injury (e.g. stroke, hypoxia/ischemia, head trauma, subarachnoid hemorrhage, and other forms of brain injury, for awakening and/or promoting the recovery of patients in various levels of coma, altered mental status or vegetative state); or for promoting recovery from chronic daily headache and migraine and related disorders via external (cutaneous) stimulation of the sensory branches of the trigeminal nerve in the face and forehead. More specifically, devices and electrode assemblies configured for stimulation of the supraorbital, supratrochlear, infraorbital, auriculotemporal, zygomaticotemporal, zygomaticoorbital, zygomaticofacial, nasal and infratrochlear nerves are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e)to the following applications: U.S. Application No. 61/248,827, entitled“Devices and Methods for Treatment of Psychiatric Disorders,” filed Oct.5, 2009; U.S. Application No. 61/289,829, entitled “ExtracranialImplantable Devices, Systems and Methods for Treatment ofNeuropsychiatric Disorders,” filed Dec. 23, 2009; U.S. Application No.61/305,514, entitled “Systems, Devices and Methods for Treatment ofNeurological Disorders and Conditions,” filed Feb. 17, 2010; and U.S.Application No. 61/354,641, entitled “Extracranial Implantable Devices,Systems and Methods for Treatment of Neurological Disorders,” filed Jun.14, 2010, and each of the above applications is hereby incorporated byreference as though fully set forth herein.

This application is also related to the following copendingapplications: U.S. application Ser. No. 12/898,685, entitled“Extracranial Implantable Devices, Systems and Methods for Treatment ofNeuropsychiatric Disorders,” filed on even date herewith with U.S.application Ser. No. 12/898,686, entitled “Devices, Systems and Methodsfor Treatment of Neuropsychiatric Disorders,” filed on even dateherewith with U.S. application Ser. No. 12/898,696, entitled“Extracranial Implantable Devices, Systems and Methods for Treatment ofNeurological Disorders,” filed on even date herewith and each of theabove applications is hereby incorporated by reference as though fullyset forth herein.

FIELD

The present disclosure generally relates to cutaneous neurostimulatorsystems, devices and methods of using the same and more particularlyrelates to cutaneous neurostimulator systems, devices and methods fortreating or promoting recovery from neurological disorders orconditions, such as seizure disorders, movement disorders, headache,acute or chronic brain injury, altered mental status/coma, and otherbrain-related disorders and conditions, by stimulating the superficialsensory branches of cranial nerves.

BACKGROUND

Neurological disorders and conditions, such as seizure disorders thatare characterized by epileptic seizures, acute or chronic brain injury,coma, chronic headache or migraine, movement and related disorders, maybe treated with medications and, in certain cases, brain surgery. Forexample, currently available treatment methods for epilepsy and otherseizure related disorders may include stimulation of the nervous systemby vagus nerve stimulation (VNS), which has been approved by the U.S.Food and Drug Administration. In this method, stimulating electrodes aresurgically implanted on the vagus nerve in the neck. In addition tocomplications related to anesthesia, potential for infection, cost, andother adverse events with VNS, many of the subjects who undergo VNStreatments do not achieve relief from their seizures, and there is noreliable predictor of good outcomes from the implanted VNS device.

Other approaches are the focus of on-going research. For example,implantable approaches, including deep brain stimulation (DBS) of theanterior thalamus and intracranial stimulation of the epileptic zone viaa device which monitors brain activity and delivers stimuli to terminatean impending seizure discharge, are also being studied. However, thesemethods are invasive and may have increased costs and side effects.Further, a substantial percentage of patients do not recover from or getadequate relief for the neurological condition or disorder despitemultiple trials of pharmaceutical or surgical treatment.

SUMMARY

One aspect of the subject matter of the present disclosure addresses theaforementioned needs by providing a method of treating neurologicaldisorders and conditions and a system and device configured to stimulatesuperficial (cutaneous) aspects of the ophthalmic (supra-orbital),infra-orbital, and mentalis branch(es) of the trigeminal nerve,specifically by providing a method of treating neurological disordersand conditions using cutaneous stimulation of the trigeminal nerve(TNS). In yet another aspect of the present disclosure, a method oftreating neurological disorders and conditions using the disclosedelectrode assembly is provided.

According to one aspect of the present invention, a method for treatinga neurological disorder or condition by trigeminal nerve stimulation isprovided. The method may include attaching an electrode assembly to apatient. The electrode assembly may include a first pair of contactsconfigured for placement on a first region of the patient's face; asecond pair of contacts configured for placement on a second region ofthe patient's face; and an insulating connection region connecting thefirst pair of contacts and the second pair of contacts, wherein thefirst pair of contacts and the second pair of contacts are configured tocontact a portion of the patient's face overlying at least one branch ofthe trigeminal nerve. The method may further include applying electricalsignals to the electrode assembly at specified operational parameters totreat a neurological disorder or condition. In some embodiments, theoperation of applying electrical signals may include applying thesignals at a frequency between approximately 20 and 300 Hertz, at apulse duration between approximately 50 and 500 microseconds, at anoutput current density of not greater than approximately 25 mA/cm²and/or an output charge density of not greater than approximately 10microCoulomb/cm² at the cerebral cortex. In some embodiments, theelectrode assembly is attached to the patient so as to contact the skinsurface over at least one of an ophthalmic or a supraorbital nerve. Insome embodiments, the neurological disorder or condition is epilepsy andother seizure related disorders. In some embodiments, the neurologicaldisorder or condition is acute or chronic brain injury. In someembodiments, the neurological disorder or condition is chronic dailyheadache and migraine and related disorders. In some embodiments, theneurological disorder is a movement disorder.

In another aspect of the present disclosure, an electrode assembly maybe configured for cutaneous trigeminal nerve stimulation. In someembodiments, the electrode assembly may be a component of a system or akit. According to one aspect of the present disclosure, a cutaneouselectrode assembly for trigeminal nerve stimulation is provided. Thecutaneous electrode assembly may include a first electrode having afirst pair of contacts configured for placement on a first region of apatient's face; a second electrode having a second pair of contactsconfigured for placement on a second region of a patient's face; and aninsulating connection region connecting the (electrodes) first pair ofcontacts and the second pair of contacts, wherein the first pair ofcontacts and the second pair of contacts are configured to contact aportion of the patient's face overlying the cutaneous distribution of atleast one branch of the trigeminal nerve for treatment of a neurologicaldisorder or condition. The at least one branch of the trigeminal nervemay be selected from the group consisting of: superficial ophthalmicbranch, infraorbital branch, and mentalis branch. In some embodiments,the electrode assembly may further include a retainer element configuredto secure the electrode assembly to a patient's forehead.

In another aspect of the present disclosure, a system for trigeminalnerve stimulation for treatment of a neurological disorder or conditionis disclosed. In one embodiment, the system includes a neurostimulatorand a cutaneous electrode assembly including: a first electrode having afirst pair of contacts configured for placement on a first region of thepatient's face; a second electrode having a second pair of contactsconfigured for placement on a second region of the patient's face; andan insulating connection region connecting the electrodes and the firstpair of contacts and the second pair of contacts, wherein the first pairof contacts and the second pair of contacts are configured to contact aportion of the patient's face overlying at least one branch of thetrigeminal nerve. The system may further include a cable and/or leadwires operably or electrically connecting the neurostimulator and thecutaneous electrode assembly. In one embodiment, the at least one branchof the trigeminal nerve is selected from the group consisting of:superficial ophthalmic branch, infraorbital branch, and mentalis branch.The system may further include a retainer element configured to securethe electrode assembly to a patient's forehead.

In another aspect, a system for trigeminal nerve stimulation fortreatment of a neurological disorder or condition is disclosed. In oneembodiment, the system includes: a pulse generator; and a cutaneouselectrode assembly in electrical communication with the pulse generator.The electrode assembly may include: a first electrode comprising atleast one contact configured for cutaneous placement at a first regionof the patient's face, wherein the first electrode is configured tocontact a portion of the patient's face overlying at least one branch ofthe trigeminal nerve, wherein the system is configured for minimalcurrent penetration into a brain of a patient, and wherein the at leastone branch of the trigeminal nerve is selected from the group consistingof: ophthalmic nerve, infraorbital nerve, mentalis nerve, supratrochlearnerve, infratrochlear nerve, zygomaticotemporal nerve, zygomaticofacialnerve, zygomaticoorbital nerve, nasal nerve, and auriculotemporal nerve.In some embodiments, the assembly further comprises a second electrodecomprising at least one contact configured for cutaneous placement at asecond region of the patient's face, wherein the second electrode isconfigured to contact a portion of the patient's face overlying at leastone branch of the trigeminal nerve, wherein the at least one branch ofthe trigeminal nerve is selected from the group consisting of:ophthalmic nerve, infraorbital nerve, mentalis nerve, supratrochlearnerve, infratrochlear nerve, zygomaticotemporal nerve, zygomaticofacialnerve, zygomaticoorbital nerve, nasal nerve, and auriculotemporal nerve.In some embodiments, the first electrode and the second electrode areconfigured to contact a portion of the patient's face overlying a samebranch of the trigeminal nerve. In some embodiments, the first electrodeand the second electrode are configured to contact a portion of thepatient's face overlying a different branch of the trigeminal nerve. Thesystem may further include a wire operably connecting the pulsegenerator and the cutaneous electrode assembly. The system may furtherinclude a regulating device configured to regulate the maximum chargebalanced output current below approximately 30-50 mA. The neurologicaldisorder or condition is selected from the group consisting of:epilepsy, seizure related disorders, acute brain injury, chronic braininjury, chronic daily headache, migraine, disorders related to migraineand headache and movement disorders. In some embodiments, the pulsegenerator is configured to apply electrical signals at a frequencybetween approximately 20 and 300 Hertz, at a pulse duration betweenapproximately 50 and 500 microseconds, at an output current density ofnot greater than approximately 25 mA/cm² and an output charge density ofnot greater than approximately 10 microCoulomb/cm² at the cerebralcortex.

In another aspect, a cutaneous electrode assembly for trigeminal nervestimulation for treatment of a neurological disorder or condition isdisclosed. In one embodiment, the assembly includes: a first electrodecomprising at least one contact configured for cutaneous placement at afirst region of the patient's face, wherein the first electrode isconfigured to contact a portion of the patient's face overlying at leastone branch of the trigeminal nerve, wherein the assembly is configuredfor minimal current penetration into a brain of a patient, and whereinthe at least one branch of the trigeminal nerve is selected from thegroup consisting of: ophthalmic nerve, infraorbital nerve, mentalisnerve, supratrochlear nerve, infratrochlear nerve, zygomaticotemporalnerve, zygomaticofacial nerve, zygomaticoorbital nerve, nasal nerve, andauriculotemporal nerve. In some embodiments, the assembly may furtherinclude a second electrode comprising at least one contact configuredfor cutaneous placement at a second region of the patient's face,wherein the second electrode is configured to contact a portion of thepatient's face overlying at least one branch of the trigeminal nerve,wherein the at least one branch of the trigeminal nerve is selected fromthe group consisting of: ophthalmic nerve, infraorbital nerve, mentalisnerve, supratrochlear nerve, infratrochlear nerve, zygomaticotemporalnerve, zygomaticofacial nerve, zygomaticoorbital nerve, nasal nerve, andauriculotemporal nerve. In one embodiments, the first electrode and thesecond electrode are configured to contact a portion of the patient'sface overlying a same branch of the trigeminal nerve. In one embodiment,the first electrode and the second electrode are configured to contact aportion of the patient's face overlying a different branch of thetrigeminal nerve. The neurological disorder or condition is selectedfrom the group consisting of: epilepsy, seizure related disorders, acutebrain injury, chronic brain injury, chronic daily headache, migraine,disorders related to migraine and headache and movement disorders.

In another aspect, a method for treating a neurological disorder orcondition by trigeminal nerve stimulation is disclosed. In oneembodiment, the method comprises: contacting a first region of apatient's face with a cutaneous electrode assembly, the cutaneouselectrode assembly comprising: a first electrode comprising at least onecontact configured for cutaneous placement at a first region of thepatient's face, wherein the first electrode is configured to contact aportion of the patient's face overlying at least one branch of thetrigeminal nerve, wherein the assembly is configured for minimal currentpenetration into a brain of a patient, and wherein the at least onebranch of the trigeminal nerve is selected from the group consisting of:ophthalmic nerve, infraorbital nerve, mentalis nerve, supratrochlearnerve, infratrochlear nerve, zygomaticotemporal nerve, zygomaticofacialnerve, zygomaticoorbital nerve, nasal nerve, and auriculotemporal nerve;and applying electrical signals to the electrode assembly at specifiedoperational parameters to treat a neurological disorder or condition. Inone embodiment, the assembly further comprises a second electrodecomprising at least one contact configured for cutaneous placement at asecond region of the patient's face, wherein the second electrode isconfigured to contact a portion of the patient's face overlying at leastone branch of the trigeminal nerve, wherein the at least one branch ofthe trigeminal nerve is selected from the group consisting of:ophthalmic nerve, infraorbital nerve, mentalis nerve, supratrochlearnerve, infratrochlear nerve, zygomaticotemporal nerve, zygomaticofacialnerve, zygomaticoorbital nerve, nasal nerve, and auriculotemporal nerve.In one embodiment, the step of applying electrical signals comprisesapplying electrical signals at a frequency between approximately 20 and300 Hertz, at a current of 0.05 to 5 milliamperes (mA) and at a pulseduration of less than or equal to 500 microseconds. In one embodiment,the step of applying electrical signals comprises applying electricalsignals at a frequency between approximately 20 and 300 Hertz, at apulse duration between approximately 50 and 500 microseconds, at anoutput current density of not greater than approximately 25 mA/cm² andan output charge density of not greater than approximately 10microCoulomb/cm² at the cerebral cortex. The neurological disorder orcondition is selected from the group consisting of: epilepsy, seizurerelated disorders, acute brain injury, chronic brain injury, chronicdaily headache, migraine, disorders related to migraine and headache andmovement disorders.

In another aspect, a kit for trigeminal nerve stimulation for treatmentof a neurological disorder or condition is disclosed. The kit mayinclude the cutaneous electrode assembly as described herein andinstructions for placement of the electrode assembly on a patient fortreatment of a neurological disorder or condition. The kit may furtherinclude a neurostimulator and instructions for applying electricalsignals to the electrode assembly for treatment of a neurologicaldisorder or condition.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, both as to its organization and manner ofoperation, may be understood by reference to the following description,taken in connection with the accompanying drawings, in which:

FIGS. 1A and 1B illustrate the location of several branches (nerves) ofthe trigeminal nerve and the location of the major foramina for thesuperficial branches of the trigeminal nerve;

FIG. 2 shows an example of a subject wearing one embodiment of acutaneous electrode assembly according to a method of neurologicaldisorder and condition treatment by TNS provided according to aspects ofthe present disclosure;

FIG. 3A is an enlarged view of the cutaneous electrode assembly of FIG.2;

FIG. 3B illustrates representative dimensions of the cutaneous electrodeassembly of FIG. 3A;

FIGS. 4A-4C depict various embodiments of the cutaneous electrodeassembly of FIG. 2;

FIG. 5 illustrates the results from a pilot study of external trigeminalnerve stimulation (“TNS”); and

FIG. 6 summarizes one embodiment of current, charge, current density andcharge density parameters for a subject exposed to cutaneous stimulationof the supraorbital nerve.

DETAILED DESCRIPTION

The present disclosure relates to methods, devices, and systems used forthe treatment of and/or promoting recovery from various neurologicaldisorders and conditions, including epilepsy and other seizure disordersand movement and other related disorders; for promoting recovery fromacute or chronic brain injury (e.g. stroke, hypoxia/ischemia, headtrauma, subarachnoid hemorrhage, and other forms of brain injury, forawakening and/or promoting the recovery of patients in various levels ofcoma, altered mental status or vegetative state); or for promotingrecovery from chronic daily headache and migraine and related disordersvia external (cutaneous) stimulation of the sensory branches of thetrigeminal nerve in the face and forehead. More specifically, devicesand electrode assemblies configured for stimulation of the sensorycomponents of the ophthalmic nerve and its branches, the infraorbitalnerve and its branches, and the mentalis nerves or its branches, andincluding the supraorbital, supratrochlear, infraorbital,auriculotemporal, zygomaticotemporal, zygomaticoorbital,zygomaticofacial, nasal and infratrochlear nerves. Methods for thetreatment of seizure disorders, such as epilepsy, and other neurologicaldisorders and conditions by eTNS (external trigeminal nerve stimulation)are also provided. The methods, systems and devices described herein maybe noninvasive or minimally invasive.

The methods, devices and systems described herein may also enhanceneurological function, alertness, attention, and cognitive functionafter various forms of brain injury, e.g., stroke, head injury,hypoxic/ischemic brain injury, and/or other forms of acute and chronicbrain injury and/or with respect to movement and other relateddisorders. The use of a cutaneous device as described herein may allowfor rapid intervention soon after brain injury thereby possiblyenhancing neurological recovery by stimulating the cutaneous branches ofthe trigeminal nerve. The unique anatomy of the trigeminal nerve, andits direct and indirect projections to key areas of the brainstem,thalamus and cortex involved with sensory processing, attention, andautonomic function, may allow the use of external stimulation for avariety of neurological conditions in which stimulation may bedesirable.

In some clinical situations, brain stimulation has been found to be ofsufficient clinical use to have been approved by the US Food and DrugAdministration, for example, electroconvulsive therapy (ECT) andrepetitive transcranial magnetic stimulation (rTMS) for psychiatricconditions. Some brain stimulation methods aim to generate currents inlarge volumes of the cortex and treat the brain as a bulk conductor, forexample, ECT at the whole-lobe level and rTMS at the large regionallevel (i.e. dorsolateral prefrontal cortex). Additionally, deep brainstimulation is generally predicated on stimulation of small but regionalvolumes that lead to discharges in a very large number of cells. Thesystems, devices and methods of the present disclosure send minimal, ifany, current into the brain; instead, signals are sent into the brain inorder to modulate the activity of relevant neuroanatomical structures.Without wishing to be bound by any particular theory, the electricalpulses generate signals in the cutaneous branches of the trigeminalnerve and the electric fields are generally confined to the skin tissueand there is minimal, if any, leakage into the brain. These electricalpulses trigger a cascade of change in neuronal signaling events thatinvolve very limited and precise recruitment of specific networks ofneurons. The neuroanatomic pathways allow targeted modulation ofactivity in areas involved in epilepsy and other neurological conditionsand disorders (e.g. locus coeruleus, anterior cingulate, insularcortex). Thus, the systems, devices and methods as disclosed hereinutilize the brain's existing infrastructure to transmit signals to thetargets of interest. In the context of this disclosure minimal currentpenetration means (1) a charge density of approximately 0 uC/cm2 at thecerebral cortex, or (2) calculated, measured, or modeled chargedensities below the following thresholds: (a) at currents, chargedensities, or charge per phase not likely to cause activation ofpyramidal neurons and axons; and (b) to prevent brain injury, a chargedensity of less than 10 uC/cm2 in one embodiment, and, in otherembodiments, a charge density of less than 0.001 to 0.1 uC/cm2, and atcombinations of charge density and charge per phase not known to causebrain injury. In some embodiments, a lower charge density may be usedwhen the central nervous system of an individual patient is sufficientlysensitive to lower levels of stimulation that the lower level will stillpermit clinical benefit to accrue.

The following description is provided to enable any person skilled inthe art to make and use the subject matter of this disclosure, and itsets forth the best modes contemplated by the inventors of carrying outthe various aspects of the disclosure. Various modifications, however,will remain readily apparent to those skilled in the art, since theprinciples of the disclosed subject matter have been defined hereinspecifically to describe: (1) systems and electrode assembliesconfigured for cutaneous trigeminal nerve stimulation; and (2) methodsof treating neurological disorders and conditions, including epilepsyand other seizure disorders, by superficial trigeminal nerve stimulationusing the electrode assembly.

For a discussion related to the trigeminal nerve, reference is firstmade to FIGS. 1A-1B, which illustrate the location of several branchesof the trigeminal nerve and the location of the major foramina for thesuperficial branches of the trigeminal nerve. The trigeminal nerve isthe largest cranial nerve and has extensive connections with thebrainstem and other brain structures. The trigeminal nerve has threemajor sensory branches over the face, all of which are bilateral, andhighly accessible. The supraorbital nerve, or ophthalmic nerve, isfrequently referred to as the V₁ division. The infraorbital branch, orthe maxillary nerve, is commonly referred to as the V₂ division. Thesuperficial branch, or the mandibular nerve (also known as the mentalisbranch), is referred to as the V₃ division. The supraorbital nervesupplies sensory information about pain, temperature, and light touch tothe skin of the forehead, the upper eyelid, the anterior part of thenose, and the eye. The infraorbital branch supplies sensory informationabout pain, temperature, and light touch sensation to the lower eyelid,cheek, and upper lip. The mentalis branch supplies similar sensorymodalities to the jaw, tongue, and lower lip.

As can be understood from FIGS. 1A and 1B, these branches exit the skullthrough three foramina. The supraorbital nerve or ophthalmic nerve exitsat foramen 1 (the supraorbital foramen or notch), approximately 2.1-2.6cm from the nasal midline (in adults), and is located immediately abovethe orbital ridge that is located below the eyebrow. The nasal nerve isa division of the ophthalmic nerve. The infraorbital branch or maxillarynerve exits at foramen 2 (the infraorbital foramen), approximately2.4-3.0 cm from the nasal midline (in adults) and the mentalis nerveexits at foramen 3 (the mentalis foramen) approximately 2.0-2.3 cm fromthe nasal midline (in adults). Other sensory branches, including thezygomaticofacial, zygomaticoorbital, zygomaticotemporal, andauriculotemporal, arise from other foramina.

Fibers from the three major branches join together to form thetrigeminal ganglion. From there, fibers ascend into the brainstem at thelevel of the pons to synapse with the main sensory nucleus of the pons,the mesencephalic nucleus of V, and the spinal nucleus and tract of V.Pain fibers descend in the spinal nucleus and tract of V, and thenascend to the ventral posterior medial nucleus (VPM) of the thalamus andthen project to the cerebral cortex. Light touch sensory fibers arelarge myelinated fibers, which ascend to the ventral posterior lateral(VPL) nucleus of the thalamus. Afferent sensory fibers project from thetrigeminal nuclei to the thalamus and the cerebral cortex.

The trigeminal nucleus has projections to the nucleus tractus solitarius(NTS), the locus ceruleus, the cerebral cortex, and the vagus nerve. TheNTS receives afferents from the vagus nerve and trigeminal nerve. NTSintegrates input from multiple sources, and projects to structures inthe brainstem and forebrain, including the locus ceruleus.

The locus ceruleus is a paired nuclear structure in the dorsal pons, andis located just beneath the floor of the fourth ventricle. The locuscoeruleus has extensive axonal projections to a broad number ofbrainstem, sub-cortical and cortical structures, and is an importantpart of the reticular activating system. The locus ceruleus is a corepart of the brainstem noradrenergic pathway, and produces theneurotransmitter norepinephrine. Norepinephrine plays a key role inattention, alertness, blood pressure and heart rate regulation, anxietyand mood.

While not wishing to be bound by any particular theory, in certainembodiments, the connections between the trigeminal nerve, locuscoeruleus, nucleus and tractus solitarius, thalamus, and cerebralcortex, may be relevant to a potential role of the trigeminal nerve innumerous neurological disorders, including coma and brain injury,seizure disorders, headache, migraine, and movement disorders, as may beapparent to one skilled in the art. Thus, cutaneous stimulation of thetrigeminal nerve at custom tailored settings and parameters within apredefined range could be effective in the treatment of multipleneurological disorders.

Neurological Disorders

Coma and Vegetative State. Subcutaneous neurostimulation may improveconsciousness in persons in coma and vegetative state. Without wishingto be bound by a particular theory, the brainstem reticular activatingsystem (including locus coeruleus) and thalamus may play a role inalerting, awakening, and activating higher cortical structures.Stimulation of these and other brain structures, to which the trigeminalnerve and nuclei project, could assist in promoting awakening in coma,as well as recovery of cognition and motor function after various formsof brain injury. Given the projections of the trigeminal nerve to keybrainstem, thalamic, and cortical structures involved in wakefulness andconsciousness, the trigeminal nerve represents one method to activatethese key structures.

Headache and Migraine. Without wishing to be bound by a particulartheory, headache and migraine involve pathways linked to the trigeminalnerve. Activation of specific trigeminal structures and pathways mayplay a role in headache. (Nature Medicine 2002; 8:136-142). Afferenttrigeminal nerve fibers from vascular structures in the pia covering thecerebral cortex are activated, and activate or sensitize the trigeminalganglion and the caudal trigeminal nuclei, which in turn activate thesuperior salvitory nucleus and the sphenopalatine ganglia. (NatureMedicine 2002; 8:136-142). Projections from these structures to vesselsin the dura mater (the outer protective lining of the brain) lead to therelease of vasoactive peptides, protein extravasation, and activation ofnitric acid pathways, all of which result in dilatation of duralvessels, which may lead to headache. This is frequently referred to asthe trigeminal-vascular reflex, and may be a mechanism in the genesis ofmigraine. (Nature Medicine 2002; 8:136-142). Without wishing to be boundby a particular theory, surgically lesioning or blocking the trigeminalnerve may inhibit this response, leading to a reduction in the cascadeof events involved with migraine and other headache syndromes. Asdisclosed herein, acute or chronic electrical stimulation of thetrigeminal nerve via its cutaneous or superficial branches in the face,at frequencies which inhibit the circuit described above, is one methodto modulate this trigeminal-vascular reflex response, and reduce orinhibit headaches or migraines in which the trigeminal nuclei and nervesplay a role.

Movement Disorders. Movement disorders are characterized by involuntarymovements of the body, and include, but are not limited to, tremors,twitches, and spasms, involuntary increases in tone of muscles, such asdystonias, and complex movements, such as dyskinesias and choreas.Without wishing to be bound by any particular theory, we hypothesizethat TNS may modulate activity in key structures involved in movementdisorders, including but not limited to the thalamus, basal ganglia,brain stem, and cerebral cortex, and may inhibit, by afferentstimulation, abnormal neuronal activity in motor systems which give riseto these involuntary phenomena.

Tardive and other Dyskinesias. Many medications which act on thedopaminergic neurons in the brain have a liability for inducinginvoluntary movements. This has been reported for treatment ofParkinson's disease with levodopa, for the use of neurolepticmedications in psychosis, bipolar disorder, and other conditions(Damier, Curr Opin Neurol 22:394-399, 2009), and for dopaminergicmedications used to address gastrointestinal symptoms (Rao andCamilleri, Ailment Pharmacol Ther 31:11-19. 2010). Other individuals maysuffer from dyskinesia on a genetic-related basis (Coubes et al., Lancet355:2220-1, 2000). These dyskinesia syndromes consist of involuntarymovements that usually start oro-facially, with the muscles of thetongue, lips, mouth or face, but can increase in severity and come toinvolve other parts of body. The exact mechanisms by which thesedyskinesias arise is not clear, but surgical treatment approaches haveimplicated the thalamus and the globus pallidum as locations where deepbrain stimulation can lead to improvement (Kupsch et al., J Neurol 250Suppl 1:147-152 2003). While not wishing to be bound by any particulartheory, the connections between the trigeminal nerve, nucleus andtractus solitarius, and thalamus may provide a mechanism by whichtrigeminal nerve stimulation can ameliorate symptoms of dyskinesia byactivating these key structures.

Seizure Disorders. Without wishing to be bound by any particular theory,trigeminal nerve stimulation may modulate activity in the locuscoeruleus, brainstem, thalamus, and cerebral cortex, and may activateinhibitory mechanisms and pathways which affect neuronal excitability.Trigeminal nerve stimulation may also inhibit excitatory mechanisms andpathways, resulting in inhibition of epileptic discharges and theirspread in cortex, and subcortical structures. These processes may have adirect or indirect effect on activity in the epileptic focus itself.

Accordingly, stimulation of the superficial or cutaneous branches of thetrigeminal nerve as disclosed herein provides an avenue for non-invasiveneuromodulation. Further, stimulation parameters can be tailored for theindividual condition, such that the brainstem, thalamic, or corticalstructures involved in the individual condition can be activated orinhibited depending on the pathophysiology of the condition beingtreated.

For a discussion of certain embodiments of methods, systems and devicesusing cutaneous electrodes according to aspects of the presentdisclosure, reference is made to FIGS. 2-4C. FIGS. 2-4C illustratevarious embodiments of a cutaneous electrode assembly and systemaccording to aspects of the present disclosure.

One sample embodiment of the present disclosure takes the form of amethod of treating epilepsy and related seizure disorders and otherneurological disorders and conditions as described herein usingtrigeminal nerve stimulation (“TNS”). Broadly speaking, the method oftreatment includes positioning external electrodes over or near at leastone of the foramina or branches of the trigeminal nerve (FIG. 1A-1B),and stimulating the electrodes using a stimulator or pulse generator fora fixed time at specified operational parameters. In one embodiment, theexternal electrodes are positioned over the foramina of the supraorbitalor ophthalmic nerves (FIG. 1A, Foramen 1) since unilateral or bilateralstimulation of the trigeminal nerve is achievable by placing single orseparate electrodes on the right and/or left sides of a patient's face(e.g. by placing an electrode assembly, such as two separate electrodes,a single paired electrode or two pairs of electrodes, over the foreheador other region of the patient's face). In one embodiment, the electrodeassembly is configured for unilateral stimulation. In one embodiment,the electrode assembly is stimulated for bilateral stimulation. In someembodiments, bilateral stimulation may offer similar or better efficacythan unilateral stimulation because the function of different brainstructures may not be the same on right and left (e.g. verbal expressionis most commonly localized to speech centers in the left hemisphere, andinjury there produces catastrophic loss of the ability to speak, whiledamage to the corresponding region on the right does not produce thisprofound loss of function, but may alter subtle functions). There mayalso be synergistic effects that arise with bilateral stimulation. FIG.2 shows an example of a patient 5 wearing an electrode assembly 10 onthe forehead, corresponding to the foramina of the ophthalmic nerves. Inalternative embodiments, the electrode assembly 10 can be positionedover the foramina of the maxillary nerves (FIG. 1A, Foramen 2) or themandibular nerves (FIG. 1B, Foramen 3). In yet other embodiments, thestimulation can be unilaterally applied to one foramen of the trigeminalnerves. In other embodiments, the method of treating epilepsy andrelated seizure disorders and other neurological disorders andconditions as described herein comprises positioning external electrodesover a plurality of foramina and simultaneously stimulating differenttrigeminal nerves. In other embodiments, electrodes may be positioned ata region of the patient's face (on the right and/or left side)corresponding with the supratrochlear nerve, infratrochlear nerve,zygomaticotemporal, zygomaticofacial, zygomaticoorbital, nasal and/orauriculotemporal nerves and/or their respective foramina.

In one embodiment, as can be understood from FIGS. 2-4C, a system 100for treatment of neurological disorders and conditions via TNS includesan electrode assembly 10, a neurostimulator or pulse generator 15 andelectrical cable or wire 20. The electrode assembly 10 may be configuredfor the bilateral simultaneous and asynchronous stimulation of theophthalmic nerves. In other embodiments, the electrode assembly may beconfigured for unilateral or bilateral stimulation of one or morebranches of the trigeminal nerve as disclosed elsewhere herein. Theneurostimulator or pulse generator may be any type of appropriatestimulating, signal-generating device. In the illustrated embodiment,the stimulator 15 is portable and attached to the belt of the patient 5.However, either a portable or non-portable stimulator can be used. Inone embodiment, the electrical cable or wire 20 is configured to providea physical and electrical link between the stimulator 15 and theelectrode assembly 10 via lead wires. In other embodiments, thestimulator 15 and the electrode assembly 10 communicate wirelessly (i.e.the wire 20 and lead wires are not used). The system 100 and/or theelectrode assembly 10 may be a part of a kit. In some embodiments, thekit may also include instructions for placement of the electrodeassembly and/or the system. In some embodiments, the kit may alsoinclude instructions for treatment of a neurological disorder orcondition according to a method disclosed herein.

The cutaneous electrode assembly 10 shown in the illustrated embodimentis also referred to as a bilateral supraorbital electrode. As shown inFIGS. 3A and 3B, the electrode assembly 10 includes a first pair ofelectrodes (also referred to as contacts) 12 a, 12 b for placement on afirst region of the patient's face, and a second pair of electrodes(also referred to as contacts) 14 a, 14 b for placement on a secondregion of the patient's face. In some embodiments, the first region isthe right side of the patient's face and the second region is the leftside of the patient's face. The first pair of contacts comprises a firstupper contact 12 a and a first lower contact 12 b, while the second pairof contacts comprises a second upper contact 14 a and a second lowercontact 14 b. An insulative connection region 16 connects the first andsecond contact pairs to each other. The electrode assembly 10 comprisesan inner contact surface 18 that comes into contact with a patient'sskin at four contact areas, each corresponding to one of the fourcontacts 12 a, 12 b, 14 a, 14 b. The inner contact surface 18 comprisingthe four contact areas may also include a buffered gel-like adhesivethat provides good electrical conductivity with minimum skin irritation,an example of such gel includes the commercially available hydrogelsfrom AmGel Technologies (AmGel Technologies, Fallbrook, Calif. USA).

Optionally, the electrode assembly 10 comprises a retainer element 24configured to secure the electrode assembly to a patient's forehead. Inone embodiment, the retainer element 24 can be an elastic band or strap.In alternative embodiments, the electrode assembly 10 can be secured inplace by a hat, band, or a cap, which may also serve to conceal theelectrode assembly from view or an appropriate adhesive.

In some embodiments, the system 100 may include a regulation device. Theregulation device is configured to be attached to the pulse generator 15and is configured to govern the maximum charge balanced output currentbelow approximately 30-50 mA to minimize current penetration to thebrain and increase patient tolerance. The regulation device may beinternally programmed to range from 0.25-5.0 mA, 0-10 mA, 0-15 mA,depending on the surface area, placement, and orientation of theelectrode, and whether the electrode is stimulating near or adjacent tothe skull, or away from the skull, (mentalis), where current ranges maybe higher or lower. Current TENS units stimulate with maximum outputcurrents of up to 100 mA's, which result in currents which may penetratethe skull and which may not be well tolerated.

The electrode assembly 10 as shown in FIGS. 3A and 3B is configured tostimulate both the right and left ophthalmic nerves eithersimultaneously or asynchronously. The insulative connection region 16serves to assist a patient in lining up the electrode assembly 10 withthe midline of the nose to ensure proper placement of the electrodeassembly 10 over both ophthalmic nerves, which lie on the average about2.1 to 2.6 cm from the nasal midline of an adult patient. Thus, theelectrode assembly can be placed accurately (e.g. by the patient)without knowledge of the location of the ophthalmic nerve or keylandmarks relative to the nerve, thereby reducing the possibility ofinadequate stimulation due to errors in positioning of the electrodes.FIGS. 4A-4C illustrate other embodiments of the electrode assembly 10,which configurations may be used to stimulate the right and/or leftophthalmic nerve and/or other branches of the trigeminal nerve asdisclosed herein, such as the zygomaticofacial and/or theauriculotemporal nerves. It can be appreciated that a single electrodeor multiple electrodes may be used. The bilateral supraorbital electrodeis configured for bilateral supraorbital stimulation. It is scalablebased on the location of use, stimulation parameters, and input fromcomputer modeling so as to negate or minimize or render safe currentpenetration into the brain. As skin irritation may occur, a similarconfiguration could be applied unilaterally, so as to provide relief toone side of the forehead, to promote skin tolerability and to reduce therisk of irritation. Other configurations of size and inter electrodedistance can be conceived for different branches of the trigeminalnerve, including but not limited to those as shown in FIGS. 4A-4C.

The placement of the first contact pair 12 a, 12 b and the secondcontact pair 14 a, 14 b on opposite sides of the nasal midline assuresthat stimulation current moves orthodromically or in the direction ofthe afferent ophthalmic or supraorbital nerve. Furthermore, thisconfiguration of the electrode assembly 10 allows the contact pairs 12a,12 b and 14 a,14 b to be stimulated independently and/or unilaterally,as the response to stimulus may be localized and thus varied from oneside of the midline to the other side. That is, the presently disclosedelectrode assembly permits individual adjustment of current for thefirst and second regions or right and left sides, as applicable, therebyreducing asymmetric stimulation and/or perceived asymmetric stimulation.

For stimulations wherein electrical pulses of a single polarity aregenerated, the upper contacts 12 a, 14 a and lower contacts 12 b, 14 bmay have fixed polarities. For stimulations wherein electrical pulses ofalternating polarities are generated, the upper contacts 12 a, 14 a andlower contacts 12 b, 14 b may have alternating polarities. Also, theinferior electrode typically serves as the cathode for the leading phaseof the stimulating pulse. In the case of a monophasic stimulation, theinferior electrode generally becomes the cathode.

FIG. 3B illustrates the dimensions of one embodiment of the cutaneous orsupraorbital electrode assembly of FIG. 2 to show the relativerelationship of the electrodes from the midline and from each other. Thesize of the electrodes and the inter-electrode distance are sized tofacilitate current delivery to the skin and nerve, while reducing and/orminimizing current density beyond the inner table ((dense layer) of theskull (inner skull bone). As explained in this disclosure, the systems,devices and methods of this disclosure are configured to minimizecurrent penetration into the brain.

Dimensions of one embodiment of the electrode assembly are shown in FIG.3B. The surface area, relationship between the electrode contacts andthe midline, and the inter-electrode distances are each importantfactors to minimize the potential for skin or nerve injury, for ensuringadequate stimulation of each nerve, and to minimize current flow(penetration) through the skull and into the brain tissue. The currentflow to the electrode, the on/off time, time of use and frequency ofstimulation are also important to ensure adequate safety and efficacy.The electrode dimensions are scalable for use with different outputcurrents and pulse duration.

As can be understood from FIG. 3B, each contact 12 a, 12 b, 14 a, 14 bis sized to deliver an electrical pulse over a large enough surface areato minimize any skin injury due to excess charge density, and tominimize current penetration beyond the inner surface of the skull bone.The distance between the first contact pair 12 a, 12 b and the secondcontact pair 14 a, 14 b is configured to stimulate the ophthalmic nerveswhile minimizing any current delivery to the surface of the brain. Inone embodiment, the mid-point of each of the electrodes is approximately2.5 cm (range 2.1-2.6 cm) from the nasal midline. The electrode size andthe inter-electrode distance may vary for children and adults, and formales and females. In one embodiment, the electrode is approximately32.5 mm in length by 12.5 mm in height and the inter-electrode distancebetween, for example, the upper pair of electrodes 12 a, 14 a is 17.5 mmand the inter-electrode distance between, for example, the upperelectrode 12 a and the lower electrode 12 b is 20 mm. In otherembodiments, the length of the electrode may be greater than or lessthan 32.5 mm and greater than or less than 12.5 mm in height. In stillother embodiments, the inter electrode distance can be in a rangegreater than 20 mm and/or less than 17.5 mm. Those of skill in the artwill recognize that one or more of the above distances can be used as aborder of a range of distances.

Those skilled in the art will appreciate that various adaptations andmodifications of the above-described embodiments of the electrodeassembly 10 are within the scope and spirit of the present disclosure.For example, one embodiment of the present device comprises a unilateralelectrode assembly configured for the unilateral stimulation ofophthalmic nerves. Also, the instant electrode assembly can also beconfigured for the stimulation of the maxillary nerves or the mandibularnerves or other nerves as disclosed herein. As yet another example, anelectrode assembly configured for the simultaneous stimulation of aplurality of trigeminal nerve branches is also within the scope of thepresent disclosure.

In use, the electrode assembly 10 is positioned over the forehead of thepatient 5 such that the insulative connection region 16 lines up withthe midline of the nose of the patient 5. In some embodiments, theelectrode assembly 10 is placed over the supraorbital foramina, locatedover the orbital ridge approximately 2.1-2.6 cm lateral to nasalmidline. In one embodiment, the electrode assembly 10 is then connectedto a pulse generator 15 via the electrical cable 20. In otherembodiments, the electrode assembly is connected to the pulse generator15 via a wireless connection. Stimulation according to patient specificoperational parameters as determined according to the methods describedherein is then applied.

According to one aspect of the present disclosure, a method of treatmentof epilepsy and related seizure disorders and other neurologicaldisorders and conditions using the electrode assembly 10, as describedabove, is described. In one embodiment, the method of treating theseneurological disorders and conditions includes positioning the electrodeassembly 10 to the forehead of a patient, connecting the electrodeassembly 10 to a stimulator, and stimulating the electrode assembly 10at defined values of the operational parameters as disclosed herein tominimize current penetration into the brain/below the skull bone. Insome embodiments, the electrode assembly is connected to the stimulatorvia wire 20 and/or lead wires. In some embodiments, the electrodeassembly is wirelessly connected to the stimulator.

In one embodiment, the bilateral supraorbital electrode 10 illustratedin FIGS. 2-3B is stimulated at a stimulus frequency between about 20 Hzand about 300 Hz, at a pulse duration between 50 microseconds (μsec) to250 μsec, at an output current density of less than approximately 25mA/cm² and at no or negligible charge densities at the cerebral cortex,or calculated or measured charge densities at the cerebral cortex ofless than 10 Uc/cm² to reduce the risk of brain injury, and less than1.0 uC/cm2, and even 0.001-0.01 uC/cm² in some embodiments, and atcombinations of charge density and charge per phase not known to causebrain injury for at least one-half to one hour per day or may beprovided for up to 24 hours per day. It is possible that even lowercharge densities may be desirable. Those of skill in the art willrecognize that one or more of the above parameters can be used as aborder of a range of parameters.

According to one aspect of the present disclosure, the method oftreating epilepsy and related seizure disorders and other neurologicaldisorders and conditions by TNS comprises selecting optimal values forthe operational parameters for the stimulation of each individualpatient. In one embodiment, the neurostimulation is provided using anelectrical stimulator at the following exemplary settings: frequency20-150 Hz, current 5-15 mA, pulse duration of 50-250 microseconds, aduty cycle of 10% to 50%, for at least one hour per day. In anotherembodiment, the neurostimulation is provided using an electricalstimulator at the following exemplary settings: frequency 20-150 Hz,current 1-10 mA, pulse duration of 50-250 microseconds, a duty cycle of10% to 50%, for at least one hour per day.

In various embodiments, the stimulation is delivered at a specific pulsewidth or range of pulse widths (or pulse duration). The stimulation canbe set to deliver pulse widths in the range greater than and/or lessthan one or more of 50 μs, 60 μs, 70 μs, 80 μs, 90 μs, 100 μs, 125 μs,150 μs, 175 μs, 200 μs, 225 μs, 250 μs, up to 500 μs. Those of skill inthe art will recognized that one or more of the above times can be usedas a border of a range of pulse widths.

In some embodiments, the stimulation amplitude is delivered as a voltageor current controlled stimulation. In other embodiments it can bedelivered as a capacitive discharge. In various embodiments, the currentamplitude can be in any range within a lower limit of about 300 μA andan upper limit of about 30 mA-35 mA, depending on the surface area ofthe electrodes, inter-electrode distance, the branch(es) stimulated, andthe modeling data as described above. In various embodiments, theamplitude can be in a range greater than and/or less than one or more of50 μA, 75 μA, 100 μA, 125 μA, 150 μA, 175 μA, 200 μA, 225 μA, 250 μA,275 μA, 300 μA, 325 μA, 350 μA, 375 μA, 400 μA, 425 μA, 450 μA, 475 μA,500 μA, 525 μA, 550 μA, 575 μA, 600 μA, 625 μA, 650 μA, 675 μA, 700 μA,725 μA, 850 μA, 875 μA, 900 μA, 925 μA, 950 μA, 975 μA, 1 mA, 2 mA, 3mA, 4 mA, 5 mA, 6 mA, 7 mA, 8 mA, 9 mA, 10 mA, 11 mA, 12 mA, 13 mA, 14mA, 15 mA, 16 mA, 17 mA, 18 mA, 19 mA and 20 mA. Those of skill in theart will recognize that one or more of the above amplitudes can be usedas a border of a range of amplitudes.

In various embodiments, the stimulation can be delivered at one or morefrequencies, or within a range of frequencies. The stimulation can beset to be delivered at frequencies less than, and/or greater than one ormore of 50 Hz, 45 Hz, 40 Hz, 35 Hz, 30 Hz, 25 Hz, 20 Hz, 15 Hz, or 10Hz. In various embodiments, the stimulation can be set to be deliveredat frequencies greater than, and/or less than, one or more of 20 Hz, 30Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 125 Hz, 150 Hz, upto 300 Hz. Those of skill in the art will recognize that one or more ofthe above frequencies can be used as a border of a range of frequencies.

In various embodiments, the stimulation is delivered at a specific dutycycle or range of duty cycles. The stimulation can be set to bedelivered at a duty cycle in the range greater than and/or less than oneor more of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%. In some embodiments, toensure preservation of the nerve, a duty cycle of 10% to 50% may bepreferable. In some embodiments, duty cycles up to 100% may be useful inparticular circumstances. Those of skill in the art will recognize thatone or more of the above percentages can be used as a border of a rangeof duty cycles.

In other embodiments, different values of the operational parameters maybe used. In one embodiment, the values of the operational parameters areselected such that a patient will experience a stimulation sensation,such as a mild tingling over the forehead and scalp without being indiscomfort or in pain. The neurostimulation parameters are importantfactors in the treatment method. In one embodiment, the values of theoperational parameters are selected to minimize skin irritation, burns,undesired effects on the brain and/or the ophthalmic nerves. In oneembodiment, the method of selecting operational parameters comprisesevaluating variables such as the configuration and size of theelectrode, the pulse duration, the electrode current, the duty cycle andthe stimulation frequency, each of which are important factors inensuring that the total charge, the charge density, and charge per phaseare well within accepted safety limits for the skin, nerve and brain.For example, to minimize skin irritation, it is not sufficient to merelyconsider the total current, but the current density needs to be defined.Additionally, it is important to select the electrical stimulationparameters, electrode design, and inter-electrode distance, such thatthe electrical stimulation zone includes the ophthalmic nerve(approximately 3-4 mm deep) or other desired nerve branch, whilepreventing or minimizing current penetration beneath the skull bone andinto the brain.

The stimulation is carried out at the above-described values of theoperational parameters. The values of the operational parameters areadvantageously selected such that a patient will experience astimulation sensation, such as mild tingling over the forehead andscalp, without causing the patient unbearable discomfort or pain and tominimize current penetration into the brain. These values may varyaccording to the treatment of interest.

In some embodiments, an external device may be used to identify thelocation of the branch or branches of the trigeminal nerve that will betargeted in an individual patient for stimulation by an implantedelectrode assembly. The external device may be used for mapping andtargeting the desired branch or branches of the trigeminal nerve and foridentifying the individual stimulation parameters that are optimal forefficacy and safety. In one embodiment, the device may include aplurality of external (transcutaneous) TNS electrodes. The practitionerapproximates the location of the target branch and affixes theelectrodes to the patient's skin above the target location. Stimulationmay be applied and the actual location or preferred (optimal)stimulation location of the target branch or branches may be determined.Stimulation parameters may also be established. Once the location and/orstimulation parameters have been established via the external device,that data may be used to help guide the placement of the implantedelectrodes for an individual patient and to establish the customizedstimulation parameters for that patient.

In addition, the use of external electrodes for stimulation of thetrigeminal nerve may identify individuals who are likely to derivetherapeutic benefit from a minimally invasive system in addition to theoptimal specific locations and parameters of stimulation based onperson-to-person variability. Various neurodiagnostic, imaging, orcutaneous nerve mapping methods may be able to delineate differences inindividual anatomy to optimize stimulation for efficacy and/or safety.Furthermore, the use of a minimally invasive system may allow screeningand identification of those individuals who are likely to derive benefitfrom other implantable systems, such as deep brain stimulation. This canbe conceptualized as linking the three approaches as stage I (externalTNS of the trigeminal nerve), stage II (implanted TNS of the superficialtrigeminal nerve), and stage III (deep brain stimulation), such thatstage I can screen for stage II, and stage II for stage III. Bymonitoring a patient for evidence of useful therapeutic effect, such asby reduction in the severity of symptoms, the results of treatment atone stage may be used to judge the likely effect of treatment with amore invasive treatment from a higher stage.

A method of evaluating the use of trigeminal nerve stimulation fortreatment of a neurological disorder in a patient is disclosed herein.The method may include applying a cutaneous system for stimulation ofthe trigeminal nerve to the patient and monitoring the patient for atleast one of evidence of a useful therapeutic response or evidence oftolerability of TNS treatment, providing a subcutaneous electrodeassembly or system, and implanting the subcutaneous electrode assemblyor system in the patient for treatment of a neurological disorder.

A method of evaluating the use of deep brain stimulation for treatmentof a neurological disorder in a patient is disclosed herein. The methodmay include applying a cutaneous system for stimulation of thetrigeminal nerve to the patient and monitoring the patient for at leastone of evidence of a useful therapeutic response or evidence oftolerability of TNS treatment thereby generating external measurementcriteria, providing a subcutaneous electrode assembly or system,implanting the subcutaneous electrode assembly or system in the patientfor treatment of a neurological disorder, monitoring the patient for atleast one of a useful therapeutic response or tolerability of theimplanted device, thereby generating extracranial measurement criteria,and analyzing the external measurement criteria and extracranialmeasurement criteria to determine whether the patient will benefit fromdeep brain stimulation.

The following examples are presented to set forth more clearly thesubject matter of this disclosure without imposing any limits on thescope thereof and to illustrate the clinical benefits of trigeminalnerve stimulation for the treatment of neurological disorders andconditions. In the examples, patients with epilepsy were treated by TNSwith external cutaneous electrodes.

EXAMPLE 1

FIG. 5 illustrates the results from a pilot study of external trigeminalnerve stimulation. Subjects with epilepsy who met inclusion andexclusion criteria for a pilot feasibility study of external trigeminalnerve stimulation initially participated in a 1-month baseline periodwhere seizures were counted, followed by active stimulation of theinfraorbital or ophthalmic branch of the trigeminal nerve. Inclusioncriteria were: subjects with poorly controlled epilepsy; ages 18-65years; at least three complex-partial or generalized tonic-clonicseizures per month; no serious or progressive medical or psychiatricconditions; and exposure to at least 2 antiepileptic drugs (AED's).Subjects with a vagus nerve stimulator were excluded from the study. Allsubjects received unblinded TNS augmentation (adjunctive) treatment forat least 8-12 hours each day. Assessments were made at study intake andat monthly periodic visits for three months following the one monthbaseline. These initial assessments were then followed-up with visits toa neurologist skilled in epilepsy for three to six month intervals forup to three years or as approved by the local Institutional ResearchCommittee.

Subjects underwent stimulation using an electrical stimulator, such asthe EMS Model 7500 commercially available from TENS Products, Inc.(www.tensproducts.com) at a frequency of 120 Hertz, a current less than20 mA, pulse duration of 250 μsec, and a duty cycle at 30 seconds on and30 seconds off, for a minimum of 8 hours.

FIG. 5 illustrates the results from this pilot study showing theeffectiveness of external trigeminal nerve stimulation. Five of twelvesubjects experienced greater than 50% reduction in adjusted mean dailyseizure rate at 6 and 12 months of treatment. Mean reduction at 3 monthswas 66% and 59% at 12 months. (DeGiorgio et al, Neurology 2009; 72:936-938). Overall, the data from the table of FIG. 5 show that thetrigeminal nerve stimulation using the described operational parametervalues was effective and well tolerated by the subjects tested. Noserious adverse events were reported. Importantly, the therapeuticeffect of the device was observed in several standard measures,indicating the broad-reaching benefits of this treatment on a variety ofoutcome measures.

EXAMPLE 2

FIG. 6 summarizes current, charge, current density and charge density ina subject exposed to cutaneous stimulation of the supraorbital nerve.FIG. 6 illustrates representative parameters for bilateral supraorbitalstimulation recorded in a subject using an EMS 7500 stimulator, 120 HZ,150-250 usec, Tyco superior silver electrodes 1.25″, one inch from themidline above the eyebrows. Data recorded with Fluke Oscilloscope, 50mV/div, resistor=10.1Ω. In general, these findings show that as thepulse width increased, the maximum tolerable current decreased.

Cutaneous electrical stimulation of the supraorbital branch of thetrigeminal nerve with round 1.25-inch TENS patch electrodes results incurrent densities and charge density/phase that are well within thelimits of safety. In general, the maximum current comfortably toleratedby TNS patients studied previously is approximately 25 mA, and patientstypically are stimulated at an amplitude setting well below 25 mA (6-10mA).

The 1.25-inch TENS electrodes are circular electrodes with a radius of1.59 cm. The surface area can be calculated as A=Πr²=[Π]×[1.59 cm]²=7.92cm². Using these electrodes, typical stimulation current ranges from6-10 mA at pulse durations of 150-250 usec.

Current Density: In a typical subject, stimulation currents of 6-10 mAresult in current densities ranging from 0.76 to 1.3 mA/cm². McCreery etal have established a maximum safe current density of 25 mA/cm at thestimulating electrode for transcranial electrical stimulation. Assumingeven higher currents of up to 25 mA with electrodes of surface area 7.92cm², current densities may range to a maximum of 3.16 mA/cm². From 0.76mA/cm² to 3.16 mA/cm², TNS delivers a current density 8-33 times lessthan the maximum safe allowable current density. Charge Density (Chargedensity/phase): Yuen et al have identified a safe limit for chargedensity/phase delivered at the cerebral cortex of 40 uC/cm² [Yuen et al1981] and more recently McCreery et al. (McCreery et al 1990) haveidentified 10 uC/cm² as the safe limit. Assuming 10 mA at 250 usec, thecharge density/phase is [0.010 A]×[250 usec]/7.92=0.32 uC/cm² at thestimulating electrode. Assuming even higher levels of stimulation, 25 mAat 250 usec, the maximum charge density per phase is 0.79 uC/cm². Atthese levels, the charge density is generally 12 to 120 fold less at thestimulating electrode than the maximum allowed at the cerebral cortex.Since the cortex is a minimum of 10-13 mm from the stimulatingelectrodes, and given the interposed layers of skin, fat, bone, dura,and CSF, the actual charge densities will be significantly lower. Thisis of importance in avoiding the undesired passage of current directlythrough brain tissue as a bulk conductor.

As shown in FIG. 6, stimulation intensity responses in a subject withelectrodes of surface area 7.92 cm2, at pulse durations between 150-250usec, results in current densities at the scalp well below currentlyrecommended current densities for transcranial stimulation, which are 25mA/cm², and charge densities at the scalp significantly lower than safecharge densities at the cerebral cortex (0.15-0.18 uC/cm²).

Those skilled in the art will appreciate that various adaptations andmodifications of the above described preferred embodiments may beconfigured without departing from the scope and spirit of thisdisclosure. Stimulation of the target nerve may be accomplished bycutaneous application of energy in many forms, such as magnetic orultrasonic. Therefore, it is to be understood that the subject matter ofthis disclosure may be practiced other than as specifically describedherein.

What is claimed is:
 1. A system for trigeminal nerve stimulation fortreatment of a neurological disorder or condition, the systemcomprising: a pulse generator; and a cutaneous electrode assembly inelectrical communication with the pulse generator, the assemblycomprising: a first electrode comprising at least one contact configuredfor cutaneous placement over or adjacent to both a foramen for asupraorbital nerve on one side of patient's forehead and a foramen for asupratrochlear nerve on the one side of the patient's forehead; a secondelectrode comprising at least one contact configured for cutaneousplacement over or adjacent to both a foramen for a remainingsupraorbital nerve on an opposing side of the patient's forehead and aforamen for a remaining supratrochlear nerve on the opposing side of thepatient's forehead; and an insulating region between the first electrodeand the second electrode.
 2. The system of claim 1, further comprising awire operably connecting the pulse generator and the cutaneous electrodeassembly.
 3. The system of claim 1, further comprising a regulatingdevice configured to regulate the maximum charge balanced output currentbelow approximately 50 mA.
 4. The system of claim 1, wherein theneurological disorder or condition is selected from the group consistingof: epilepsy, seizure related disorders, acute brain injury, chronicbrain injury, chronic daily headache, migraine, disorders related tomigraine and headache and movement disorders.
 5. The system of claim 1,wherein the pulse generator is configured to apply electrical signals ata frequency between approximately 20 and 300 Hertz, at a pulse durationbetween approximately 50 and 500 microseconds, at an output currentdensity of not greater than approximately 25 mA/cm² and an output chargedensity of not greater than approximately 10 microCoulomb/cm² at thecerebral cortex.
 6. A method for treating a neurological disorder orcondition by trigeminal nerve stimulation, comprising: aligning aninsulative region of a cutaneous electrode assembly with the nasalmidline of a patient, the insulative region configured to insulate afirst contact for the cutaneous electrode assembly from a second contactfor the cutaneous electrode assembly; contacting the patient's foreheadwith the aligned cutaneous electrode assembly such that the firstcontact is over or adjacent to both a foramen for a supraorbital nerveon one side of the patient's forehead and a foramen for a supratrochlearnerve on the one side of the patient's forehead and such that the secondcontact is over or adjacent to both a foramen for a remainingsupraorbital nerve on an opposing side of the patient's forehead and toa foramen for a remaining supratrochlear nerve on the opposing side ofthe patient's forehead; and applying electrical signals to the electrodeassembly contacting the patient's forehead at specified operationalparameters to treat a neurological disorder or condition.
 7. The methodof claim 6, wherein the step of applying electrical signals comprisesapplying electrical signals at a frequency between approximately 20 and300 Hertz, at a current of 0.05 to 5 milliamperes (mA) and at a pulseduration of less than or equal to 500 microseconds.
 8. The method ofclaim 6, wherein the step of applying electrical signals comprisesapplying electrical signals at a frequency between approximately 20 and300 Hertz, at a pulse duration between approximately 50 and 500microseconds, at an output current density of not greater thanapproximately 25 mA/cm² and an output charge density of not greater thanapproximately 10 microCoulomb/cm² at the cerebral cortex.
 9. The methodof claim 6, wherein the neurological disorder or condition is selectedfrom the group consisting of: epilepsy, seizure related disorders, acutebrain injury, chronic brain injury, chronic daily headache, migraine,disorders related to migraine and headache and movement disorders.
 10. Akit for trigeminal nerve stimulation for treatment of a neurologicaldisorder or condition, the kit comprising: the cutaneous electrodeassembly according to claim 1; and instructions for placing theelectrode assembly on a patient for treatment of a neurological disorderor condition.
 11. The kit of claim 10, further comprising: a pulsegenerator; and instructions for applying electrical signals to theelectrode assembly for treatment of a neurological disorder orcondition.